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1.
Perspect Public Health ; : 17579139221138451, 2022 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-36583536

RESUMO

AIMS: The middle-out perspective (MOP) provides a lens to examine how actors positioned between government (top) and individuals (bottom) act to promote broader societal changes from the middle-out (rather than the top-down or bottom-up). The MOP has been used in recent years in the fields of energy, climate change, and development studies. We argue that public health practitioners involved with advocacy activities and creating alliances to amplify health promotion actions will be familiar with the general MOP concept if not the formal name. The article aims to demonstrate this argument. METHODS: This article introduces the MOP conceptual framework and customises it for a public health audience by positioning it among existing concepts and theories for actions within public health. Using two UK case studies (increasing signalised crossing times for pedestrians and the campaign for smoke-free legislation), we illustrate who middle actors are and what they can do to result in better public health outcomes. RESULTS: These case studies show that involving a wider range of middle actors, including those not traditionally involved in improving the public's health, can broaden the range and reach of organisations and individuals involving in advocating for public health measures. They also demonstrate that middle actors are not neutral. They can be recruited to improve public health outcomes, but they may also be exploited by commercial interests to block healthy policies or even promote a health-diminishing agenda. CONCLUSION: Using the MOP as a formal approach can help public health organisations and practitioners consider potential 'allies' from outside traditional health-related bodies or professions. Formal mapping can expand the range of who are considered potential middle actors for a particular public health issue. By applying the MOP, public health organisations and staff can enlist the additional leverage that is brought to bear by involving additional middle actors in improving the public's health.

2.
Mol Psychiatry ; 23(3): 629-638, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-28348387

RESUMO

Adult neurogenesis in the dentate gyrus (DG) is strongly influenced by drug-taking behavior and may have a role in the etiology of drug-seeking behavior. However, mechanistic studies on the relationship of neurogenesis on drug seeking are limited. Outbred Wistar rats experienced extended access methamphetamine self-administration and individual differences in drug taking defined animals with higher preferred and lower preferred levels of drug intake. Forced abstinence from higher preferred levels of drug taking enhanced neurogenesis and neuronal activation of granule cell neurons (GCNs) in the DG and produced compulsive-like drug reinstatement. Systemic treatment with the drug Isoxazole-9 (a synthetic small molecule known to modulate neurogenesis in the adult rodent brain) during abstinence blocked compulsive-like context-driven methamphetamine reinstatement. Isoxazole-9 modulated neurogenesis, neuronal activation and structural plasticity of GCNs, and expression of synaptic proteins associated with learning and memory in the DG. These findings identify a subset of newly born GCNs within the DG that could directly contribute to drug-seeking behavior. Taken together, these results support a direct role for the importance of adult neurogenesis during abstinence in compulsive-like drug reinstatement.


Assuntos
Comportamento de Procura de Droga/efeitos dos fármacos , Isoxazóis/farmacologia , Neurogênese/efeitos dos fármacos , Tiofenos/farmacologia , Animais , Encéfalo/efeitos dos fármacos , Giro Denteado/efeitos dos fármacos , Comportamento de Procura de Droga/fisiologia , Individualidade , Aprendizagem/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Metanfetamina/efeitos adversos , Neurônios/efeitos dos fármacos , Ratos , Ratos Wistar , Recidiva , Autoadministração , Transtornos Relacionados ao Uso de Substâncias/tratamento farmacológico
3.
Drug Alcohol Depend ; 175: 179-186, 2017 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-28437722

RESUMO

BACKGROUND: Immunotherapies directed against methamphetamine (MA) abuse have shown success in rodent models, however only a limited number of studies have investigated active vaccination in female mice and none in female rats. It is critical to determine if potential immunotherapeutic strategies generalize across sex, particularly for drugs that may produce significant sex-differences on behavioral or physiological endpoints. METHODS: Female Wistar rats were initially vaccinated with keyhole-limpet hemocyanin (KLH) or an anti-methamphetamine-KLH conjugate (MH6-KLH) three times over five weeks and implanted with radiotelemetry devices to assess locomotor activity and body temperature responses to MA. Rats were first exposed to MA via vapor inhalation (100mg/mL in propylene glycol) and then by injection (0.25-1.0mg/kg, i.p.) and vapor after a final vaccine boost. RESULTS: The MH6-KLH vaccine generated an increase in antibody titers across the initial 6-week, 3 immunization protocol and a restoration of titer after a week 14 booster. Locomotor stimulation induced by 0.25mg/kg MA, i.p, in the KLH group was prevented in the MH6-KLH group. MH6-KLH animals also exhibited an attenuated locomotor stimulation produced by 0.5mg/kg MA, i.p. No group differences in locomotion induced by vapor inhalation of MA were observed and body temperature was not differentially affected by MA across the groups, most likely because vapor inhalation of MA that produced similar locomotor stimulation resulted in ∼10-fold higher plasma MA levels. CONCLUSIONS: This study confirms the efficacy of the MH6-KLH vaccine in attenuating the effects of MA in female rats.


Assuntos
Adjuvantes Imunológicos/administração & dosagem , Transtornos Relacionados ao Uso de Anfetaminas/prevenção & controle , Hemocianinas/administração & dosagem , Metanfetamina/efeitos adversos , Vacinação/métodos , Vacinas/administração & dosagem , Animais , Feminino , Imunização/métodos , Metanfetamina/administração & dosagem , Ratos , Ratos Wistar
4.
Chem Commun (Camb) ; 52(22): 4187-90, 2016 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-26906286

RESUMO

3,4-Diaminopyridine has shown promise in reversing botulinum intoxication, but poor pharmacokinetics and a narrow therapeutic window limit its clinical utility. Thus, we developed a pH-dependent oral delivery platform using club moss spore exines. These exine microcapsules slowed 3,4-diaminopyridine absorption, limited its seizure activity, and enabled delivery of doses which prolonged mouse survival after botulism neurotoxin A intoxication.


Assuntos
4-Aminopiridina/análogos & derivados , Toxinas Botulínicas Tipo A/intoxicação , Cápsulas , Lycopodium/química , 4-Aminopiridina/administração & dosagem , 4-Aminopiridina/farmacocinética , Administração Oral , Amifampridina , Microscopia Eletrônica de Varredura
5.
Drug Alcohol Depend ; 153: 29-36, 2015 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-26118833

RESUMO

BACKGROUND: d-Methamphetamine (METH) addiction is a serious public health concern for which successful treatment remains elusive. Immunopharmacotherapy has been shown to attenuate locomotor and thermoregulatory effects of METH. The current study investigated whether active vaccination against METH could alter intravenous METH self-administration in rats. METHODS: Male Sprague-Dawley rats (Experiment 1: N=24; Experiment 2: N=18) were vaccinated with either a control keyhole-limpet hemocyanin conjugate vaccine (KLH) or a candidate anti-METH vaccine (MH6-KLH) or. Effects of vaccination on the acquisition of METH self-administration under two dose conditions (0.05, 0.1mg/kg/inf) and post-acquisition dose-substitution (0, 0.01, 0.05, 0.20mg/kg/inf, Experiment 1; 0.01, 0.05, 0.10, 0.15mg/kg/inf, Experiment 2) during steady-state responding were investigated. Plasma METH concentrations were determined 30min after an acute challenge dose of 3.2mg/kg METH. RESULTS: Active vaccination inhibited the acquisition of METH self-administration under the 0.1mg/kg/inf dose condition, with 66% of the MH6-KLH-vaccinated rats compared to 100% of the controls reaching criteria, and produced transient and dose-dependent effects on self-administration during the maintenance phase. Under the 0.05mg/kg/inf dose condition, MH6-KLH-vaccinated rats initially self-administered more METH than controls, but then self-administration decreased across the acquisition phase relative to controls; a subsequent dose-response assessment confirmed that MH6-KLH-vaccinated rats failed to acquire METH self-administration. Finally, plasma METH concentrations were higher in MH6-KLH-vaccinated rats compared to controls after an acute METH challenge, and these were positively correlated with antibody titers. CONCLUSIONS: These data demonstrate that active immunopharmacotherapy for METH attenuates the acquisition of METH self-administration.


Assuntos
Comportamento Aditivo/prevenção & controle , Hemocianinas/administração & dosagem , Metanfetamina/análogos & derivados , Metanfetamina/administração & dosagem , Vacinação/métodos , Animais , Comportamento Aditivo/psicologia , Relação Dose-Resposta a Droga , Infusões Intravenosas , Masculino , Metanfetamina/antagonistas & inibidores , Ratos , Ratos Sprague-Dawley , Autoadministração , Resultado do Tratamento , Vacinas/administração & dosagem
6.
Biol Trace Elem Res ; 167(2): 320-5, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25774045

RESUMO

There are many reports of the positive effect of yerba mate on the human body. Elemental composition analysis of yerba mate revealed the presence of many microelements and macroelements, but there is no literature data referencing the content and the effect of the method of preparing the yerba mate infusion on the amount of released fluoride and thus the amount of this element supplied to the human body. Therefore, in the traditional way (cold and hot), we prepared infusions of yerba mate from different countries and determined in samples content of fluoride using potentiometric method. Hot infusions resulted in statistically significant (p = 0.03) increases in the amount of fluoride released from the dried material to the water, compared to brewing with water at room temperature. The successive refills of hot water also resulted in a release of the same amount of fluoride, although smaller than the infusion with water at room temperature (at the third refill, it was statistically significantly smaller at p = 0.003). With an increase in the number of hot water refills, the amount of fluoride released from the sample portion significantly decreased. Similar results were recorded when analyzing samples depending on the country of origin. The amount of fluoride released into the water differed statistically significantly depending on the country of origin. The most fluoride was determined in the infusions of yerba mate from Argentina and the least in infusions from Paraguay.


Assuntos
Fluoretos/análise , Análise de Alimentos , Ilex paraguariensis/química , Argentina , Humanos , Paraguai
8.
Phys Chem Chem Phys ; 10(48): 7226-32, 2008 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-19060966

RESUMO

We report transient grating measurements carried out on single crystals of bromine clathrate hydrates and on bromine dissolved in water. In all cases, excitation into the B-state of Br2 leads to prompt predissociation, followed by cage-induced recombination on the A/A' electronic surfaces. In liquid water, the vibrationally incoherent recombinant population peaks at t=1 ps and decays with a time constant of 1.8 ps. In the hydrate crystals, the recombination is sufficiently impulsive to manifest coherent oscillations of the reformed bond. In tetragonal TS-I crystals, with the smaller cages, the recombination is fast, t=360 fs, and the bond oscillation period is 240 fs. In cubic CS-II crystals, the recombination is slower, t=490 fs, and the visibility of the vibrational coherence, which shows a period of 290 fs, is significantly reduced due to the larger cages and the looser fit around bromine. The mechanical cage effect is quantified in terms of the recombination time-distribution, the first three moments of which are associated with size, structural rigidity, and anelasticity of the cage. In the crystalline cages, the distribution is symmetric about the mean: mean time tm=300 fs, 400 fs and standard deviation sigma=70 fs, 100 fs, in TS-I and CS-II, respectively. The finding is consistent with the assignment of occupied cages: principally 5(12)6(2) polyhedra in TS-I and 5(12)6(4) polyhedra in CS-II. In liquid water, with diffuse cages, the distribution characterized by tm=555 fs and sigma=400 fs, is strongly skewed (gamma1=1.88) toward delayed recombination-the effective liquid phase hydration shell is larger than that in a hydrate phase, structurally disordered, and anelastic. Information about dipolar disorder, comparable in all three media, is extracted from electronic predissociation rates of the B-state, which is sensitive to the symmetry in the guest-host interaction.

9.
J Phys Chem A ; 112(5): 787-9, 2008 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-18181590

RESUMO

The structure and composition of bromine clathrate hydrate has been controversial for more than 170 years due to the large variation of its observed stoichiometries. Several different crystal structures were proposed before 1997 when Udachin et al. (Udachin, K. A.; Enright, G. D.; Ratcliffe, C. I.; Ripmeester, J. A. J. Am. Chem. Soc. 1997, 119, 11481) concluded that Br2 forms only the tetragonal structure (TS-I). We show polymorphism in Br2 clathrate hydrates by identifying two distinct crystal structures through optical microscopy and resonant Raman spectroscopy on single crystals. After growing TS-I crystals from a liquid bromine-water solution, upon dropping the temperature slightly below -7 degrees C, new crystals of cubic morphology form. The new crystals, which have a limited thermal stability range, are assigned to the CS-II structure. The two structures are clearly distinguished by the resonant Raman spectra of the enclathrated Br2, which show long overtone progressions and allow the extraction of accurate vibrational parameters: omega(e) = 321.2 +/- 0.1 cm(-1) and omega(e)x(e) = 0.82 +/- 0.05 cm(-1) in TS-I and omega(e) = 317.5 +/- 0.1 cm(-1) and omega(e)x(e) = 0.70 +/- 0.1 cm(-1) in CS-II. On the basis of structural analysis, the discovery of the CS-II crystals implies stability of a large class of bromine hydrate structures and, therefore, polymorphism.

10.
Phys Chem Chem Phys ; 8(39): 4550-8, 2006 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-17047752

RESUMO

A full-dimensional quasi-classical trajectories study on the vibrational predissociation (VP) of the Ne79Br2(B) complex is presented. Following the most recent experiments, the Br2(B) vibrational levels v'=16-29 were explored. The total angular momentum, J, was taken to be zero, and a semiclassical Franck-Condon model to compute initial conditions from quantum distributions was employed. Predissociation lifetimes were extracted from Ne79Br2 population decay by using two different exponential laws. Predicted lifetimes are in excellent agreement with the last experimental results [J. A. Cabrera, C. R. Bieler, B. C. Olbricht, W. E. van der Veer and K. C. Janda, J. Chem. Phys., 2005, 123, 054311]. The Br2 fragment ro-vibrational distributions resulting from the VP of the molecule were obtained from the statistics of classical magnitudes using the standard binning procedure. Computed rotational distributions (for the Deltav'=-1, -2 channels) are also in very good agreement with the experimental results [M. Nejad-Sattari and T. A. Stephenson, J. Chem. Phys., 1997, 106 5454]. The influence of two quantum effects-the closing of the Deltav'=-1 dissociation channel and the intramolecular vibrational relaxation (IVR) mechanism-on the agreement with experimental rotational distributions, is discussed. Due to the classical character of our calculations and the binning procedure we used, the agreement of computed vibrational distributions with experimental and quantum theoretical is qualitative. For instance, for v'=28-for which the Deltav'=-1 channel is experimentally found to be closed-the Deltav'=-2 channel becomes statistically more significant. A discussion on the viability of similar quasi-classical methods to model the VP dynamics of analogous clusters is presented.

11.
Int J Artif Organs ; 29(8): 736-44, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16969750

RESUMO

An increasing body of evidence suggests that atherosclerosis in patients with uremia differs from that found in general population in terms of advancement and localization of vascular lesions. It has also been suggested that different non-invasive techniques of vascular system evaluation are designed to show different types of lesions (i.e. vascular calcification, stiffness or 'classical' atherosclerosis). The aim of the study was to search for possible associations between results obtained with three different non-invasive methods of vascular system assessment in three different vascular sites in patients treated with peritoneal dialysis (PD). 61 patients (28 F, 33 M), mean age of 50.4+/-13.6 years, on maintenance PD for a median period of 10 months (range 1-96 months) were included. Coronary artery disease (CAD) was present in 21 subjects. In all subjects coronary artery calcification score (CaSc) using multi-row spiral computed tomography (MSCT), aortic pulse wave velocity (AoPWV) and ultrasound-based common carotid artery intima-media thickness (CCA-IMT) were performed as methods for assessing coronary calcium burden, arterial stiffness and atherosclerosis, respectively. Median value of CaSc equaled 11.5 Agatston units (range 0-5502.8 units). Median AoPWV was 10.4 m/s (range 7.56-18.1 m/s), and median CCA-IMT-0.6 mm (range 0.3-1.0 mm). In 16 patients (26.2%) at least one plaque in at least one common carotid artery was found on ultrasound. CaSc correlated with AoPWV (R=0.32, p<0.01) and with CCA-IMT (R=0.35, p<0.005), whereas no association was found between AoPWV and CCA-IMT. AoPWV, but not CaSc nor IMT correlated with blood pressure. The values of CCA-IMT and AoPWV increased together with consecutive Agatston categories (with p<0.001 for differences in AoPWV and p<0.05 for CCA-IMT). Patients with at least one plaque found in at least one CCA and patients with CAD were characterized with significantly higher values of CaSc, IMT and PWV, when compared to plaque-free and CAD- negative subjects, respectively. Association between CaSc and both IMT and PWV may suggest that the mechanism of three assessed vascular pathologies may be based, to some extent, on the process of pathologic calcium-phosphate deposition. Lack of correlation found between PWV and IMT may suggest that aortic stiffness and carotid atherosclerosis may partially differ in their pathologic background and/or are dissociated in time.


Assuntos
Aorta/fisiopatologia , Doenças das Artérias Carótidas/diagnóstico por imagem , Artéria Carótida Primitiva/diagnóstico por imagem , Doença da Artéria Coronariana/diagnóstico por imagem , Diálise Peritoneal , Túnica Íntima/diagnóstico por imagem , Túnica Média/diagnóstico por imagem , Velocidade do Fluxo Sanguíneo/fisiologia , Pressão Sanguínea/fisiologia , Calcinose/classificação , Calcinose/diagnóstico por imagem , Doenças das Artérias Carótidas/fisiopatologia , Artéria Carótida Primitiva/fisiopatologia , Doença da Artéria Coronariana/classificação , Elasticidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fluxo Pulsátil/fisiologia , Tomografia Computadorizada Espiral , Túnica Íntima/fisiopatologia , Túnica Média/fisiopatologia , Ultrassonografia
12.
J Chem Phys ; 124(20): 204507, 2006 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-16774353

RESUMO

In both water and in ice, the absorption spectra of bromine are dramatically broadened and blueshifted, and all fluorescence is quenched. Time resolved, electronically resonant transient grating measurements are carried out to characterize the vibronic dynamics of the trapped molecule in its electronic B(3Pi0u) state in ice. Independent of the initial excitation energy, after the first half-period of motion, a vibrational packet is observed to oscillate near the bottom of the potential, near nu=1. The oscillations undergo a chirped decay to a terminal frequency of 169 cm(-1) on a time scale of taunu=1240 fs, to form the stationary nu=0 level. The electronic population in the B state decays in taue=1500 fs. Adiabatic following to the cage-compression coordinate is a plausible origin of the chirp. Analysis of the absorption spectrum is provided to recognize that solvent coordinates are directly excited in the process. The observed blueshift of the absorption is modeled by considering the Br2-OH2 complex. Two-dimensional simulations, that explicitly include the solvent coordinate, reproduce both the time data and the absorption spectrum. The observed sharp vibrational recursions can be explained by overdamped motion along the solvent coordinate, and wave packet focusing by fast dissipation during the first half-period of motion of the molecular coordinate.

13.
J Chem Phys ; 124(3): 034305, 2006 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-16438581

RESUMO

Wave-packet simulations of the Ne-Br2(B,upsilon') vibrational predissociation dynamics in the range upsilon' = 16-29 are reported. The aim is to interpret recent time-dependent pump-probe experiments [Cabrera et al., J. Chem. Phys. 123, 054311 (2005)]. Good agreement is found between the calculated and the experimental lifetimes corresponding to decay of the Ne-Br2(B,upsilon') initial state and to appearance of Br2(B,upsilon

15.
Int J Artif Organs ; 26(3): 188-95, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12703883

RESUMO

Increased aortic pulse wave velocity (AoPWV) has been identified as a risk factor for cardiovascular morbidity in the general population and in patients on dialysis. Most of the studies in ESRD patients refer to subjects on hemodialysis. Influence of the inflammatory process on aortic stiffening remains largely unknown. The aim of the present study was to evaluate potential relationships between AoPWV and blood pressure, basic anthropometric parameters, selected growth factors and markers of the inflammatory process in ESRD patients treated with peritoneal dialysis. The study population consisted of 43 patients (19 F, 24 M) with a mean age of 50.6 +/- 13.4 years on PD for a mean period of 21.9 +/- 20.7 months. AoPWV was measured using two pressure transducers placed on the carotid and femoral arteries and connected to an automatic processor (Complion Colson AS, Paris, France). Serum levels of Tumor Necrosis Factor alpha (TNFalpha), interleukin 6 (IL-6) and plasma basic Fibroblast Growth Factor (bFGF) were measured with ELISA; C-reactive protein and fibrinogen with nephelometry. Serum lipid profile was also assessed. Blood pressure was measured in an outpatient department under standardized conditions. Mean aortic pulse wave velocity in the study population was 10.7 +/- 2.1 m/s. No difference in AoPWV was found between men and women. AoPWV correlated significantly with age (R = 0.41; p < 0.01) but not with time on dialysis. Positive relationship between AoPWV and body weight and BMI was shown (R = 0.31; p < 0.05 and R = 0.35; p < 0.05, respectively). AoPWV correlated significantly with systolic blood pressure (SBP), mean arterial pressure (MAP) and pulse pressure (PP) (R = 0.46, p < 0.005, R = 0.46, p < 0.005 and R = 0.43, p < 0.01, respectively). AoPWV correlated with serum IL-6 and plasma bFGF (R = 0.32, p < 0.05 and R = 0.4, p < 0.01; respectively). The correlation with serum CRP was borderline significant (p < 0.53). In multiple regression analysis age (beta 0.38; p < 0.005), plasma bFGF level (beta 0.3; p < 0.05), and systolic blood pressure (beta 0.29; p < 0.05) were independently associated with pulse wave velocity. Our results suggest that AoPWV values in patients on PD are associated with factors similar to those encountered in the general population. We suggest that increased aortic stiffening may also be related to the chronic inflammatory process in PD patients.


Assuntos
Aorta/fisiologia , Pressão Sanguínea/fisiologia , Inflamação/fisiopatologia , Falência Renal Crônica/imunologia , Diálise Peritoneal/métodos , Fluxo Pulsátil/fisiologia , Proteínas de Fase Aguda/análise , Adolescente , Adulto , Idoso , Antropometria , Aorta/fisiopatologia , Biomarcadores/sangue , Doença Crônica , Citocinas/sangue , Feminino , Substâncias de Crescimento/sangue , Humanos , Falência Renal Crônica/fisiopatologia , Falência Renal Crônica/terapia , Masculino , Pessoa de Meia-Idade
16.
J Am Chem Soc ; 125(9): 2489-506, 2003 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-12603137

RESUMO

The exo and endo Diels-Alder adducts of p-methoxycarbonylbenzyl trans-1,3-butadiene-1-carbamate and N,N-dimethylacrylamide have been synthesized, and the absolute configurations of resolved enantiomers have been determined. On the basis of this information, the absolute enantioselectivities of the Diels-Alder reaction catalyzed by antibodies 13G5 and 4D5 as well as other catalytic antibodies elicited in the same immunizations have been established. The effects of different arrangements of catalytic residues on the structure and energetics of the possible Diels-Alder transition states were modeled quantum mechanically at the B3LYP/6-311++G**//B3LYP/6-31+G** level of theory. Flexible docking of these enantiomeric transition states in the antibody active site followed by molecular dynamics on the resulting complexes provided a prediction of the transition-state binding modes and an explanation of the origin of the observed enantioselectivity of antibody 13G5.


Assuntos
Acrilamidas/química , Anticorpos Catalíticos/química , Butadienos/química , Sequência de Aminoácidos , Anticorpos Catalíticos/genética , Cristalografia por Raios X , Ciclização , Compostos Ferrosos/imunologia , Haptenos/imunologia , Cinética , Metalocenos , Modelos Moleculares , Conformação Molecular , Dados de Sequência Molecular , Estrutura Molecular , Teoria Quântica , Estereoisomerismo , Termodinâmica
17.
Science ; 293(5536): 1806-11, 2001 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-11546867

RESUMO

Recently we reported that antibodies can generate hydrogen peroxide (H2O2) from singlet molecular oxygen (1O2*). We now show that this process is catalytic, and we identify the electron source for a quasi-unlimited generation of H2O2. Antibodies produce up to 500 mole equivalents of H2O2 from 1O2*, without a reduction in rate, and we have excluded metals or Cl- as the electron source. On the basis of isotope incorporation experiments and kinetic data, we propose that antibodies use H2O as an electron source, facilitating its addition to 1O2* to form H2O3 as the first intermediate in a reaction cascade that eventually leads to H2O2. X-ray crystallographic studies with xenon point to putative conserved oxygen binding sites within the antibody fold where this chemistry could be initiated. Our findings suggest a protective function of immunoglobulins against 1O2* and raise the question of whether the need to detoxify 1O2* has played a decisive role in the evolution of the immunoglobulin fold.


Assuntos
Anticorpos Catalíticos/metabolismo , Peróxido de Hidrogênio/metabolismo , Oxidantes/metabolismo , Oxigênio/metabolismo , Água/química , Água/metabolismo , Animais , Anticorpos Catalíticos/química , Sítios de Ligação , Catálise , Sequência Conservada , Cristalografia por Raios X , Humanos , Cinética , Modelos Moleculares , Oxidantes/química , Oxirredução , Conformação Proteica , Oxigênio Singlete , Espectrometria de Massas por Ionização por Electrospray , Termodinâmica , Triptofano/metabolismo , Raios Ultravioleta , Xenônio/metabolismo
18.
Bioorg Med Chem ; 9(9): 2253-7, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11553463

RESUMO

A new approach for the elicitation of metal-dependent catalytic antibodies for ester hydrolysis is described. A coordinatively unsaturated mercury complex 1-(Hg), has been utilized as a hapten to elicit antibodies that incorporate mercury(II) as a Lewis acid cofactor. From a panel of monoclonal antibodies generated to 1-(Hg), antibody 38G2 was found to hydrolyze the ester 3 in the presence of HgCl(2) [K(m)app(3)=345 microM; K(m)app(Hg(2+))=87 microM; k(cat)app/k(uncat)=3 x 10(2)]. This is the first example of a biocatalyst that enlists mercuric ion as a cofactor and it is anticipated that this approach will open new avenues for exploitation of metals thought previously beyond the scope of protein catalysts.


Assuntos
Aciltransferases/imunologia , Anticorpos Catalíticos/química , Metais/imunologia , Aciltransferases/antagonistas & inibidores , Aciltransferases/metabolismo , Anticorpos Catalíticos/efeitos dos fármacos , Anticorpos Catalíticos/imunologia , Anticorpos Monoclonais/química , Anticorpos Monoclonais/efeitos dos fármacos , Anticorpos Monoclonais/imunologia , Inibidores Enzimáticos/farmacologia , Haptenos/química , Haptenos/imunologia , Hidrólise/efeitos dos fármacos , Concentração Inibidora 50 , Cinética , Mercúrio/imunologia , Modelos Moleculares , Fosfatos/síntese química , Fosfatos/química , Fosfatos/imunologia
20.
J Am Chem Soc ; 123(34): 8248-59, 2001 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-11516276

RESUMO

Antibody 38C2 catalyzed a retro-aldol process upon dendritic modified aliphatic polyesters. This catalytic system was studied in detail and displayed rate enhancements, k(cat)/k(uncat), of greater than 10(6). These antibody-catalyzed reactions took place in a stepwise manner yielding partially modified aldol-dendrimers until a fully substituted aldehyde dendrimer was formed. The catalytic antibody 38C2 only reacted with surface-exposed aldol moieties and did not significantly interact with the core groups for dendrons 4 and 8. For a higher generation dendron 8 the rate of unmasking slightly decreased presumably due to steric crowding of the aldol functionalities. In addition, catalytic antibody 38C2 was able to selectively differentiate block-hybrid dendrons and was regiospecific in the retro-aldol reaction of dendron 21. This is an inaugural report of a catalytic antibody utilizing dendrimers as substrates and suggests that antibodies could be used as selective catalysts for the controlled release and activation of specific molecules attached to biodegradable polymeric materials. Furthermore, this is the first example of catalytic antibody 38C2 displaying regioselectivity on a multifunctional aldol substrate. Important for synthetic applications is the antibody's ability to selectively differentiate regions on dendritic substrates and produce partly aldol functionalized dendrons under conditions mild enough to avoid beta-elimination.


Assuntos
Anticorpos Catalíticos/química , Benzaldeídos/química , Materiais Biocompatíveis/síntese química , Poliésteres/síntese química , Materiais Biocompatíveis/química , Hidroxiácidos , Poliésteres/química , Propionatos/química
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